The present invention relates generally to voice changers and more specifically to a unique voice changer for use with a telephone.
There are many situations in which a person does not wish their voice to be recognized. Historically, devices have been attached to the mouthpiece of the hand set of a telephone to alter the voice being picked up by the microphone in the hand set. This is generally a physical modification of the voice signal. These devices typically produce a muffled voice and have not generally changed the frequency content. Thus, one could still generally identify the speaker as male or female.
At least one digital voice changer is available. This is a hand held unit into which one speaks and has an output device which is mounted over the mouth piece of a telephone handset.
Women living alone generally use only the initial of their first name in telephone listings and mail boxes for personal security. An unknown caller could detect the sex of the answerer and thus defeat the purpose of the telephone listing. Also, in front door security intercoms, the occupant would reveal their sex by answering on the intercom.
There has been a substantial amount of research in analyzing voice signals for speech synthesizers as well as controlling other devices by recognition of speech commands. Depending upon the controls to be operated, the amount of words which must be recognized is determined. For general controls, for example, UP-DOWN, RIGHT-LEFT or ON-OFF, the recognition of a substantial number of different kinds of voices for these commands can be recognized. As the amount of words to be recognized increases, the memory required, as well as the sophistication of the circuit, and the ability to recognize different speakers saying those same words, becomes substantially more difficult. An example of such a sophisticated system is a typewriter or word processing unit which is voice actuated. Most recently, these systems are produced and then tailored for the individual operator. This would not allow another operator to use the same terminal. This restricts their use and increases, unnecessarily, the cost of the unit or requires more units, one for each operator.
There has been much research conducted on speech synthesizers which break speech into multiple components, store them in a digital computer, and reproduces specific messages as required. These have been included in household appliances, automobiles and other consumer devices. Small integrated circuits have been developed which will convert an 8-bit I/O data port into a high quality speech port. This is done for example, using a continuously variable slope-delta modulation to encode and decode wave forms under the direction of a microprocessor. Such a chip is available from Motorola as MC-3518. By changing the time constant elements of the circuit including data rate, a change in the frequency range of the encoder occurs. Historically, the frequency range has been changed to improve the quality and match the voice of the speaker or to minimize the storage at the cost of voice quality.
It is an object of the present invention to provide an electronic voice changer for real-time use.
Another object of the present invention is to provide a voice changer which is connected between the hand set and the telephone set.
A still further object of the present invention is to provide an inexpensive voice changer which may be easily inserted between the hand set and the telephone set.
A still further object of the present invention is to provide a real-time voice changer which allows selectible varying of the frequency content of the voice signal such that the sex of the voice has been changed.
A still further object is to provide a voice changer which provides security by changing the apparent sex of the speaker on a telephone or intercom.
An even further object of the present invention is to provide a voice changer for use with voice actuated controls to make them more universal.
These and other objects are achieved by providing a voice changing having a first port for connection to a microphone, a second port connectible to a speaker, and a voice changing circuit for selectively changing the frequency content of the voice signal transmitted between the first and second ports. The voice changing circuit includes selection capability for selecting either (1) no voice change; (2) a high frequency change; or (3) a low frequency change. The frequency change may change a male to a female voice or a female to a male voice or any variation in between.
The voice changer uses analog to digital converter connecting the first port to a microprocessor through a serial to parallel converter wherein the digitized voice signals are stored and played back through a parallel to serial converter and a digital to analog converter whose output is connected to the second port. Clock circuits drive these elements in real-time. By varying the frequency of the clock pulses, the frequency content of the encoded and decoded speech is varied. The clock which drives the analog to digital converter and serial to parallel converter is driven at a fixed rate, and a second clock that drives the parallel to serial converter and the digital to analog converter is a variable clocks.
When the voice changer is used with a telephone, the first port is connected to the hand set or speaker, and the second port is connected to the telephone. The microphone signals are processed by the voice changer and the speaker signals are connected directly between the first and second ports without a modification. Depending upon the signals, an input amplifier may be required and an output amplifier and interface circuit, for example a transformer, may be required.
The voice changer may also be used on an intercom to change the occupant's voice from that of a woman to a man and thereby providing security as well as mask the identity. Another environment for the voice changer is its use in a voice control environment. With word processors or automatic typewriters, the voice changer could be connected between the microphone and the analysis unit. By adjusting the voice changer, all incoming voices, even though they vary in frequency, will be in a defined frequency range.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.